Edible pharmaceutical ink and process of using same



n d States aten EDIBLE PHARMACEUTICAL INK AND PROCESS OF USING SAME The present invention is directed to the production of certain ink bases and ink compositions suitable for marking coated pharmaceutical tablets. Especially the present invention is concerned with ink and processes when the ink is applied to a coated medicinal core. Such a core is defined for purposes of this invention as having a compacted-and compressed straight sided base containing an active pharmaceutical in suitable dosage which is rounded and smoothed by the addition of multiple smoothing, grossing and/or other coatings.

Preferably as described in my related application Serial No. 333,147, filed January 26, 1953, an intermediate printing base of shellac or other suitable filmforming material is interposed between the coated medicinal core and the ink brand or indicia and said indicia is further protected by a protective transparent overcoating of for example wax or other suitable material.

It has been further suggested that due to the stickiness or tackiness of shellac when used as a printing base that a lubricative plasticizer be added in amounts of about 310% to the weight of the dry shellac. A preferred plasticizer is an acetylated monoglyceride containing two acetic acid groups and one long chain fatty acid group per fat molecule, as prepared according to United States Letters Patent No. 2,615,159-Jackson.

Other operable plasticizers which impart a lubricous quality to the printing base are monoglycerides of higher fatty acids or higher molecular weight fatty alcohols. The purpose of such a plasticizer is to prevent adherence of the printingbase to the coating pan, which sometimes causes the pulling of the coating from the medicinal core and renders the tablet unsightly and possibly unsalable. The plasticizer also causes the core to flow smoothly through the grading mechanism and imprinting feeding mechanism, and, to seat properly in the cups of the printing machine. In addition to its lubricative value, such a plasticizer is of value in that it materially improves the receptivity of the ink indicia imprinted on the printing base and assists the bonding at the printing base-indicia interface. castor oil, and stearic acid'were unsatisfactory it is theorized that a preferred plasticizer, such as said acetylated monoglycen'de on drying of the printing base is expelled to the outside of the printing base layer due to the increase in the water/alcohol ratio following the faster evaporation of alcohol. Thus the preferred plasticizer which is partially compatible with the printing base is kicked out to the surface layer where it can exert its lubricative properties. The details of the improvements are further set out in my related application Serial No. 539,111, now US. 2,865,810, Sanders, filed October 7, 1955.

It has been further found that it was advisable to reduce the amount of tack or blocking of shellac when used in the printing base and this was done by adding to the preferred two-component, shellac-plasticizer composition described above, a suitable quantity, preferably about 30% by weight, of. the prolamine protein zein. -To a preferred-printing base composition a small amount of urea and water may be added for clarity since the urea probably combines with free terminal carboxyl- Since certain plasticizers such as Patented Aug. 9,1960.

7 2 v groups in the shellac, as described in United States Letters Patent No. 2,678,278--Schmutzler. Thisdevelopment is more clearly described in my co-pending application Serial No. 698,020-Sanders, filed November 4, 1957. a

Among other resinous printing base compositions which are suitable by reason of their edible, non-toxic and filmforming characteristics are: cellulose ethers such as hydroxy ethyl cellulose, described in United States Patent No. 2,693,436-Spradling, and No. 2,816,062Doerr, and sodium carboxymethyl cellulose described in Patent No. 2,693,437-Spradling, and Patent No. 2,816,061 Doerr; cellulose esters and mixed ester ethers as exemplified by Patent No. 2,433,244-Springett; analogous cellulose derivatives; polyvinyl pyrrolidone; polyvinyl alcohol; polyvinyl acetate; and natural resinous substances such as sandarac, balsam and gelatin.

It became a problem to develop inks which would be compatible with the marked pharmaceutical tablet and process developed. Several criteria for the ink wer necessary. I

It is therefore a primary. object of the present invention to provide an edible ink which is compatible with the resinous film-forming coatings which comprise the printing bases. y

It is a further object of the present invention to develop an ink which would be alcohol soluble but naphtha insoluble so that this ink would bite or bond to the printing base but would not be dissolved by a waxnaphtha transparent overcoat.

It is a further object, of the invention to develop inks with a satisfactory elfective no smudge drying time of about three to four seconds from the time of branding to the collection hopper or barrel. I

It is a further object of this invention to develop shellac based inks having a critical zein/shellac ratio.

The prior art into which the inks of the "present invention falls may be distinguished. US. Patents 2,236,- 521, Coleman, and 2,185,117, Coleman, teach generally zein ink compositions and specially zein ink compositions in particular oxygenated solvents. Also U.S. Patents 2,338,151, Weber, and 2,360,382., weber, describe zein/ shellac printing ink bases. In the latter patent at'page 2, column 1, which is probably the clos'esfprior art, the definite statement is made that in the solid content of the solution, either the shellac or the zein may vary from about 15% to about of the total zein and shellac. Contrastingly, in the compositions of the present invention the analogous zein/shellac weight ratio is critically less than .10 or 10% and preferably in the range of about .02 to .08 or 2 to 8%.

Furthermore, there is no teaching in the prior art of dewaxed shellac ink compositions developed specially for imprinting on "a shellac or shellac/zein printing base on a coated medicinal core or a pharmaceutical tablet.

The process of marking the tablets is a very exacting one in the preparation of tabletshaving 'a' satisfactory pharmaceutically elegant appearanceJ Generally, tablets to which the special printing base has been'app'lied are fed from a rotary drum feeding mechanism which dc posits the tablets in cups on a moving belt.' The inking of the tablets is carried out by a transfer 'roller which deposits the ink by an offset process. Subsequently the tablets move along the belt and are removed by' mechanical means such as by a rake or compressedair'blas't conventional polishing pans and a transparent wax overcoat is applied from a mixture of carnauba wax and beeswax in a suitable solvent.

A number of problems had to be solved in the development of satisfactory pharmaceutical inks as disclosed herein.

Initially, it was decided that due to favorable solvent conditions and the desirability of a like on like printing on the presently preferred shellac or shellac/zein printing base of the pharmaceutical tablets that a shellac based ink should be utilized.

Firstly, it was found that under the particular conditions involved in making pharmaceutical tablets that a satisfactory quick drying solvent be used for the ink. Among the alcoholic solvents available, isopropyl alcohol and butyl alcohol were tested but found to be unsatisfactory as too slow drying. A satisfactory solvent for the inks was found in certain special ethyl alcohol compositions; namely, 95% ethyl alcohol (U.S.P.) plus 5% methyl alcohol or preferably 95 ethyl alcohol (U.S.P.) plus 5% ethyl acetate.

Furthermore, due to the interfering waxy constituents in orange shellac, a dewaxed shellac is preferably employed in the inks of the invention. Such a dewaxed shellac is the product which remains after solvent extraction of wax. Dewaxed shellac has an acid number of about 60 (mg. KOH necessary to neutralize 1 gm.) and is thermoplastic having a tack point of about 205 F.

Such a dewaxed shellac may be conveniently employed in a confectioners glaze (dewaxed) which is 2.8# dewaxed shellac/ gallon of alcoholic solution wherein the alcoholic solution is as before defined.

Additionally, it was found that special pigments incorporated in the ink compositions gave optimum results. For example, with the black inks of the present invention a black pigment of particle size of about 21 mg (millimicrons) known as double bolted impingement type black was used. Also with the white inks, a titanium dioxide pigment passing a 325 mesh screen (44 was successfully utilized. Such a pigment is known as titanium dioxide (anatase type) drug and cosmetic grade. Similar special pigments or lakes were utilized to produce red, green, blue, orange, lavender and light brown inks.-

It has been further found that an addition of a critical amount of zein to the ink composition produced an ink which decreased the drying time of the ink to a point where spotting or smudging of the inks in the collection hopper no longer occurred. Now especially in consideration of the black and white inks, when calculated on a dry. basis for the ink base composition, it was found that the addition of zein in amount so that the zein/ shellac ratio on the dry basis was up to .10 and preferably in the range of about 0.02 to 0.08 gave protection from spotting which otherwise occurred, produced a satisfactory pharmaceutical ink imprint within the requisite drying time of three to four seconds. It is to be noted that where the drying time was too slow, spotting or smudging of the tablets occurred in the containers and when the drying time was too fast an insufiicient transfer occurred and further the ink tended to clog the engraving and the transfer rollers.

The zein/shellac ratio of about 0.02 to 0.08 calculated for the dry ink base gave optimum transfer characteristics both for the extra fast dry ink used for the larger engravings utilizing a higher zein content and for the relatively slower dry ink suitable for the smaller engravings. Tests showed that where a formulation of shellac without zein was used spotting of the tablets occurred and when a zein/ shellac ratio in excess of 0.10 or in a 4 ratio of about 0.12 or 0.14 was used then severe clogging of the engraving occurred.

The following examples illustrate the compositions and processes of the present invention.

Example 1.Preparati0n of black ink The entire weight of pigment (double bolted impingement type black) was weighed and deposited into a suitable container. Sufficient confcctioners glaze (about onehalf the total amount) was added to form a high viscosity liquid. The pigment-shellac mixture was then mixed under high shear with an air driven mixer to break-up large agglomerations of pigment. After termination of this pre-mixing, additional confectioners glaze was added (about one-fourth the total amount) to reduce the viscosity sufficiently to permit efiicient grinding in the ball mill. Grinding was effected in the ball mill for at least one hour to assure mixture of the shellac-pigment product and to reduce agglomerate size.

The balance of the confectioners glaze and a minor amount of water (1%) was added to the total weight of zein and stirred slowly with very slight warming until solution was complete. The solution was filtered and added to the pigment-shellac mixture with additional mixing before placing the finished ink composition in containers.

Example 2.Preparation of white ink Wet composition:

6% carbon dust (double bolted impingement black) 2% zein (MazeinCorn Products Refining Company) 32% shellac (dewaxed) 58.69% ethyl alcohol (95 U.S.P.--Permit 3A or 35A) 1.31% water The above ink had a volatile (liquid) content of 60.6% and a non-volatile solids content of 39.4%.

Based upon the non-volatile 39.4% solids content this ink had the following solids percentages.

Dry basis:

15% carbon black 5% zein dry shellac (dewaxed) 100% This ink had a zein/shellac weight ratio of 0.062.

Example 4.Black ink (fast dry) for small engravings- Composition 55 The following ink composition was prepared according to the method of Example 1.

5.2% carbon black (double bolted impingement black) 1.0% Zein 33.1% shellac (dewaxed) 60.2% ethyl alcohol ethyl alcohol (U.S.P.)

Permit 3A or 35A) .5% water The above ink had a volatile (liquid) content of 60.7% and a non-volatile solids content of 39.3%.

Based upon the non-volatile 39.3% solids content, this ink had the following solids percentages Dry basis:

13.2% carbon black 2.5% zein 84.3% dry shellac (dewaxed) This ink had a zein/shellac weight ratio of 0.029.

Example 5 .-White ink (very fast dry)-Compositi0n 21 The following ink was prepared according to the procedure of Example 2.

Wet composition:

The above ink had a volatile (liquids) content of 40.4% and a non-volatile solids content of 59.6%.

Based upon the non-volatile solids content of 59.6%, this ink had the following solids percentages.

Dry basis:

60.4% titanium dioxide 37.1% shellac (dewaxed) 2.5% zein titanium dioxide (anatase type) shellac (dewaxed) ethyl alcohol (95% (U.S.P.)) zein water 100.0% This ink has a zein/shellac weight ratio of 0.067.

Example 6.White ink (fast dry)-C0mp0siti0n 23 The following ink was prepared according to the procedure of Example 2.

Wet composition:

36.0% titanium dioxide (anatase type) .75% zein 22.36% shellac (dewaxed) 4 0.64% ethyl alcohol (95% (U.S.P.))

.25% water The above ink had a volatile (liquid) content of 40.7% and a non-volatile solids content of 59.1%.

Based upon the non-volatile 59.1% solids content, this ink had the following solids percentages.

Dry basis:

60.9% titanium dioxide 1.27% zein 37.83% shellac (dewaxed) zein. Additionally a minor amount otf a non-ionic surtactant may be utilized in the order of up to 1%, such as for example a condensation product of isooctyl phenol with ethylene oxide.

Having thus described my invention, it is understood that the present invention is limited only by the scope of the appended claims and modifications and equivalents which can be included within the scope of this invention.

I claim:

1. A fast drying edible ink for applying indicia to resinous film-forming outer coated pharmaceutical tablets which consists essentially of dewaxed shellac, zein, a color forming substance selected from pigments and lakes, and ethyl alcohol wherein the zein/shellac Weight ratio is in the range of about 0.02 to 0.10.

2. A fast drying edible ink for applying indicia to shellac coated pharmaceutical tablets which consists essentially of dewaxed shellac, zein, a pigment and 95 ethyl alcohol wherein the zein/shellac weight ratio is in the range of about 0.02 to 0.08.

3. An ink according to claim 2 wherein the pigment is carbon black.

4. An ink according to claim 2, wherein the pigment is titanium dioxide.

5. An edible ink composition for marking shellac coated pharmaceutical tablets consisting essentially of about 5 to 6% carbon dust, 1 to 2% zein, 32 to 33% dewaxed shellac and balance 95% ethyl alcohol solvent wherein the zein/shellac weight ratio is in the range of about .02 to .08.

6. An edible ink composition for. marking shellac' coated pharmaceutical tablets consisting essentially of about 36% titanium dioxide, 0.75 to 1.5% zein, 22% dewaxed shellac and balance 95 ethyl alcohol wherein the zein/shellac weight ratio is in the range of about .02110 .08.

7. In the method of imprinting indicia on a coated pharmaceutical tablet having a resinous film-forming outer printing surface, the steps which comprise imprinting on said surface with an edible ink consisting essentially of a color forming substance selected from pigments and lakes, dewaxed shellac and zein in a 95 ethyl alcoholic solvent wherein the zein/shellac weight ratio is in the range of about 0.02 to 0.10.

8. In the method of imprinting indicia on a coated pharmaceutical tablet having an outer printing surface selected from the group consisting of shellac and shellac/ zein mixtures, the steps which comprise imprinting on said surface with an edible ink consisting essentially of a pigment, dewaxed shellac and zein in a 95 ethyl alcoholic solvent wherein the zein/shellac weight ratio is in the range of about 0.02 to 0.08.

9. The method according to claim 8 wherein the pigment is carbon black.

10. The method according to claim 8 wherein the pigment is titanium dioxide.

11. The method according to claim 8 wherein the ink is applied at a controlled temperature of about 68-72 F. and a humidity of about 4555%.

References Cited in the file of this patent UNITED STATES PATENTS 2,236,521 Coleman Apr. 1, 1941 2,338,151 Weber Ian. 4, 1944 2,360,382 Weber Oct. 17, 1944 2,678,278 Schmutzler May 11, 1954 2,865,810 Sanders Dec. 23, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. $948,626 August 9, 1960 Roy Y. Sanders, Jr.

It is herebfi certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 18 before "became" insert now line 55 for "or" read of g column 3 line 34, for "2.8 read 2,8 column 6. line 1 for; "otf" read of line 15,

claim l, and line 44, claim 7', after 0.02"; each occurrence, insert up Signed and sealed this 31st day of January 1961,

(SEAL) Attest:

KARL AXLINE ROBERT (J. WATSON Attesting Officer Commissioner of Patents 

1. A FAST DRYING EDIBLE INK FOR APPLING INDICIA TO RESINOUS FILM-FORMING OUTER COATED PHARMACEUTICAL TABLETS WHICH CONSISTS ESSENTIALLY OF DEWAXED SHELLAC, ZEIN, A COLOR FORMING SUBSTANCE SELECTED FROM PIGMENTS AND LAKES, AND 95% ETHYL ALCOHOL WHEREIN THE ZEIN/SHELLAC WEIGHT RATIO IS IN THE RANGE OF ABOUT 0.02 TO 0.10. 